The floor plan of the Stomorica Church in Zadar resembles a key, and according to tradition, it symbolizes St Peter's keys. Today only the base of that hexafoil Pre-Romanesque church, which was once dedicated to St Ursula, is preserved.
The Stomorica Church had a cupola as well, and instead of one apse it had a rectangular base with a bell tower. It was demolished in the 16th century and buried to serve as a part of fortifications. At the end of the 19th century, it was researched by archaeologists, then buried again at the end of the 19th century, and then, finally, in 1966 it was excavated and preserved.